I used to use a Rojak Ladder Stopper for pitched roofs that weren't too deep; it meant I could use the ladder at an unsafe angle, safer (not safely).
But to be honest, avoid this stuff while using ladders - it really isn't worth the risk of falling - and she sounds like she's 'price conscious' (aka a tight pain in the bottom) if she's already got a window cleaner.
And in the medium term, look to go WFP, jobs like that are a doddle with a pole; really easy.
HTH